[The effect of intraoperative warming on patient core temperature].

OBJECTIVE: To investigate the influence of using fluid warming and forced-air warming system on patient core temperature, blood loss, blood transfusion, extubation time, and postoperative shivering.

METHODS: Forty ASA (American Society of Anesthesiologists' Physical Status) I-II patients, aged 21-69 years, scheduled for elective abdominal surgery under general anesthesia, were enrolled in the study. The patients were premedicated with intramuscular dolantin 50 mg and atropine 0.5 mg. Anesthesia was induced with midazolam 1 mg, fentanyl 50-100 microg and propofol 1.5-2.0 mg/kg. Tracheal intubation was facilitated with vecuronium 1mg and succinylcholine 1.5-2.0 mg/kg. The patients were mechanically ventilated and anesthesia was maintained with isoflurane 1.5-2.0%, 50% N2O in oxygen and intermittent iv boluses of fentanyl (total dose 5-6 microg/kg). Vecuronium was used for muscle relaxation during maintenance of anesthesia. The patients were randomly divided into 2 groups: control group (n = 20) and warming group (n = 20). In both groups, the patients were covered with surgery blanket. In the warming group, patients were additionally warmed with fluid warming device and forced-air warming system during the operation. The core temperature was recorded every 20 minutes during the operation, as well as the blood loss, blood transfusion, extubation time and postoperative shivering.

RESULTS: The core temperature at the end of the surgery was (36.4 +/- 0.4) degrees C in the warming group and (35.3 +/- 0.5) degrees C in the control group. The difference was statistically significant (t = 7.547, P < 0.001). There was no significant difference of blood loss and blood transfusion between two groups. The extubation time was significantly shorter in the warming group [(18 +/- 6) vs (26 +/- 10) min, t = -3.364, P = 0.002]. 6 patients shivered postoperatively in the control group and none in the warming group (chi2 = 7.059, P = 0.008).

CONCLUSION: Fluid warming system and forced-air warming system can effectively maintain normothermia during the surgery and then help to reduce the extubation time and postoperative shivering.